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| United States Patent |
5,592,668
|
|
Harding
, et al.
|
January 7, 1997
|
Method and apparatus for specifying a query to an information system
using natural language-like constructs
Abstract
Computerized tools for modeling database designs and specifying queries of
the data contained therein. Once it is determined that an information
system needs to be created, the Fact Compiler of the present invention is
invoked to create it. After creating the information system, the user
creates a fact-tree as a prelude to generating queries to the system.
After creating the fact-tree, the user verifies that it is correct using
the Tree Interpreter of the present invention. Once the fact tree has been
verified, the Query Mapper of the present invention is used to generate
information system queries.
| Inventors:
|
Harding; James A. (Issaquah, WA);
McCormack; Jonathan I. (Renton, WA)
|
| Assignee:
|
Asymetrix Corporation (Bellevue, WA)
|
| Appl. No.:
|
488384 |
| Filed:
|
June 6, 1995 |
| Current U.S. Class: |
707/2 |
| Intern'l Class: |
G06F 017/30 |
| Field of Search: |
395/600,161,12,155
|
References Cited
U.S. Patent Documents
| 4506326 | Mar., 1985 | Shaw et al. | 395/600.
|
Other References
Anick, P. G., et al. "A Direct Manipulation Interface for Boolean
Information Retrieval via Natural Language Query" ACM SIGIR '90, pp.
135-150, Sep. 1990.
Czejdo, B., et al., "A Graphical Data Manipulation Language for an
Entity-Relationship Model" IEEE Computer, pp. 26-36, Mar. 1990.
Czejdo, B., et al. "A Visual Query Language for an ER Data Model" 1989 IEEE
Workshop on Visual Languages pp. 165-170, 1989.
Kamel, M., et al., "A Graph Based Knowledge Retrieval System" IEEE Int'l
Conf. on Systems, Mana, and Cybernetics, pp. 269-275, 1991.
Sockut, G. H., et al. "GRAQULA: A Graphical Query Language for
Entity-Relationship or Relational Databases" IBM Research Report
(#73,833), Mar. 14, 1991.
Young, D. et al. "A Graphical Filter/Flow Representation of Boolean
Queries: A Prototype Implementation and Evaluation" J. Am. Soc. for
Information Science, vol. 44, No. 6, pp. 327-339, Jul. 1993.
Keim, D. A., et al. "Visual Query Specification in a Multimedia Database
System" Proc. IEEE 1992 Conf. on Visualization pp. 194-201, 1992.
|
Primary Examiner: Black; Thomas G.
Assistant Examiner: Wang; Peter Y.
Attorney, Agent or Firm: LaRiviere, Grubman & Payne
Parent Case Text
This application is a division of application Ser. No. 08/112,852, filed
Aug. 25, 1993, now U.S. Pat. No. 5,495,604.
Claims
What is claimed is:
1. Apparatus including a general purpose programmable digital computer,
said computer having central processing means, bus means, display means,
data entry means, memory means, data storage means, and graphical user
interface for describing in a natural language a query to a database, said
apparatus further comprising:
diagram means for producing a diagram on said display means;
cursor control means for moving a cursor over said diagram;
repository means further comprising relational database means implemented
on said computer;
fact tree formation means for forming a fact tree based on said query; and
fact tree description means for describing said fact tree in said natural
language, said fact tree description means including
(a) first variable assignment means for assigning variables based on said
fact tree, said variables comprising root, parent, child and node, wherein
said root is the root of said fact tree, said parent is the parent of said
root, said child is the child of the root and said node is the number of
the child,
(b) parent test means for testing if a value of said parent is null,
(c) root text creation means, responsive to a determination by said parent
test means that said value of said parent is null, for creating text for
said root,
(d) node text creation means, responsive to a determination by said parent
test means that a value of said parent is not null, for creating text for
said node,
(e) print means for printing, on said display means, said text created by
said root text creation means and said node text creation means,
(f) counter means for counting an iteration as an iteration value,
(g) node test means for determining if said iteration value is equal to a
value of said node, and
(h) recursive means for recursively invoking said fact tree description
means using depth-first search means.
2. The apparatus of claim 1, wherein said root text creation means further
comprises:
second variable assignment means for assigning variables based on said fact
tree, said variables comprising first noun, first restriction and first
text wherein said first noun is the noun in said root, said first
restriction is the restriction in said root and said first text is equal
to the value of said noun and a phrase indicating totality;
first restriction test means for testing if a value of said first
restriction is null;
first text modification means, responsive to a determination by said first
restriction test means that a value of said first restriction is not null,
for modifying said first text to be equal to said text and a word or
phrase indicating presentation;
second text modification means, responsive to a determination by said first
restriction test means that a value of said restriction is null, for
modifying said text to be equal to said text and said noun and said
restriction and a word or phrase indicating presentation; and
first text return means for returning said text as modified by said first
or said second text modification means to said fact tree description
means.
3. The apparatus of claim 1, wherein said node text creation means further
comprises:
third variable assignment means for assigning variables based on said fact
tree, said variables comprising second noun, parent-noun, phrase, second
restriction and second text wherein said second noun is a noun in said
root, said parent-noun is a noun in said root's parent, said phrase is a
phrase of said root, said restriction is a restriction in said root and
said second text is equal to said second noun added to said parent-noun
added to said phrase;
second restriction test means for testing if a value of said second
restriction is null;
third text modification means, responsive to a determination by said second
restriction test means that a value of said restriction is not null, for
modifying said text to be equal to said second text added to said second
noun added to said second restriction;
child testing means for testing if said root has said child;
fourth text modification means, responsive to a determination by said child
test means that said root has said child, for modifying said text to be
equal to said text added to said noun; and
second text return means for returning said text to said fact tree
description means.
4. Method for describing, in a natural language, a query to a database
previously implemented on a general purpose programmable digital computer,
said computer comprising central processing means, bus means, display
means, data entry means, memory means, data storage means, graphical user
interface and repository means further comprising relational database
means implemented on said computer, said description method further
comprising the steps of:
producing a diagram on said display means;
moving a cursor over said diagram;
forming a fact tree based on said query; and
describing said fact tree in said natural language, said step of describing
said fact tree further comprising the steps of
(a) assigning variables based on said fact tree, said variables comprising
root, parent, child and node, wherein said root is the root of said fact
tree, said parent is the parent of said root, said child is the child of
the root and said node is the number of the child using a first variable
assignment method,
(b) testing if a value of said parent is null using a parent test method,
(c) creating text for said root using a root text creation method,
responsive to a determination by said parent test method that said value
of said parent is null,
(d) creating text for said node using a node text creation method,
responsive to a determination by said parent test method that a value of
said parent is not null,
(e) printing, on said display means, said text created by said root text
creation method and said node text creation method using a print method,
(f) counter method for counting an iteration as an iteration value,
(g) determining if said iteration value is equal to a value of said node
using a node test method, and
(h) recursively invoking said fact tree description method using a
depth-first recursive search method.
5. The method of claim 4, said root text creation method further comprising
the steps of:
assigning variables based on said fact tree, said variables comprising
first noun, first restriction and first text, wherein said first noun is
the noun in said root, said first restriction is the restriction in said
root and said first text is equal to the value of said first noun and a
phrase indicating totality using a second variable assignment method;
testing if a value of said first restriction is null using a first
restriction test method;
modifying said first text to be equal to said first text having and a word
or phrase indicating presentation using a first text modification method,
said first text modification method responsive to a determination by said
first restriction test method that a value of said first restriction is
not null;
modifying said text to be equal to said text and said noun and said
restriction and a word or phrase indicating presentation using a second
text modification method, said second text modification method responsive
to a determination by said first restriction test method that a value of
said restriction is null; and
returning said text as modified by said first or said second text
modification method to said fact tree description method using a first
text return method.
6. The method of claim 4, wherein said node text creation method further
comprises the steps of:
assigning variables based on said fact tree, said variables comprising
second noun, parent-noun, phrase, second restriction and second text
wherein said second noun is a noun in said root, said parent-noun is the
noun in root's parent, said phrase is the phrase of the root, said second
restriction is a restriction in said root and said second text is equal to
said second noun added to said parent noun added to said phrase, said
method of assigning variables using a third variable assignment method;
testing if a value of said restriction is null using a second restriction
test method;
modifying said text, responsive to a determination by said second
restriction test method that a value of said restriction is not null, to
be equal to said text added to said noun added to said restriction, using
a third text modification method;
testing if said root has said children using a child testing method;
modifying said text, responsive to a determination by said child testing
method that said root has said children; and
second text return method for returning said text to said fact tree
description method.
7. A method for defining a query of an information system, the information
system having been created using drag-and-drop information system
specification means utilizing a computer language having both textual and
graphical forms for translating the natural language-like constructs into
object-role modeling symbology, the specification means further for
entering text onto the display device utilizing the textual form of the
computer language, for parsing the text into at least one of object, fact
and constraint into the repository, and for forming a conceptual schema
diagram representing the information system on the display device
utilizing the graphical form of the computer language, and for mapping the
conceptual schema to a database, the apparatus implemented on a
programmable computer including memory, data entry means, data display
means, a graphical user interface, and having a repository implemented
thereon, the apparatus using natural language-like constructs for querying
the information system and further comprising:
means for displaying the conceptual schema utilizing the graphical form of
the computer language;
drag and drop cursor control means for moving a cursor over the conceptual
schema diagram, and for selecting a first object therefrom;
fact tree formation means for forming a fact tree from a first object
stored in the repository and displayed on the conceptual schema diagram,
the first object forming the root node of a fact tree; and
fact tree description means for describing the fact tree with natural
language-like constructs on the data display means, utilizing the textual
form of the computer language.
8. The apparatus of claim 7 wherein:
the cursor control means is further for selecting at least one fact
relevant to the first object from the conceptual schema display means; and
the fact tree formation means is further for forming the fact tree from the
first object and the fact, the fact forming a child node of the root node.
9. The apparatus of claim 7 wherein:
the cursor control means is further for selecting a constraint relevant to
the first object from the conceptual schema display means; and
the fact tree formation means is further for forming the fact tree from the
first object and the constraint, the constraint limiting the object.
10. Method for defining a query of an information system, the information
system having been created using drag-and-drop information system
specification means utilizing a computer language having both textual and
graphical forms for translating the natural language-like constructs into
object-role modeling symbology, the specification means further for
entering text onto the display device utilizing the textual form of the
computer language, for parsing the text into at least one of object, fact
and constraint into the repository, and for forming a conceptual schema
diagram representing the information system on the display device
utilizing the graphical form of the computer language, and for mapping the
conceptual schema to a database, the apparatus implemented on a
programmable computer including memory, data entry means, data display
means, a graphical user interface, and having a repository implemented
thereon, the apparatus using natural language-like constructs for querying
the information system and further comprising the steps of:
displaying the conceptual schema the display device utilizing the graphical
form of the computer language;
moving a cursor over the conceptual schema diagram with a drag and drop
cursor control means, and selecting a first object from the diagram;
forming a fact tree from a first object stored in the repository and
displayed on the conceptual schema diagram, the first object forming the
root node of a fact tree; and
describing the fact tree with natural language-like constructs on the data
display means utilizing the textual form of the computer language.
11. The method of claim 10 further comprising the steps of:
selecting at least one fact relevant to the first object from the
conceptual schema display means; and
forming the fact tree from the first object and the fact, the fact forming
a child node of the root node.
12. The method of claim 10 further comprising the steps of:
selecting a constraint relevant to the first object from the conceptual
schema display means, the constraint limiting the object; and
forming the fact tree from the first object and the constraint.
Description
TECHNICAL FIELD
This invention relates to the creation of computer database systems and the
querying of data contained therein. In particular, the invention relates
to computerized tools for modeling database designs and specifying queries
of the data contained therein.
BACKGROUND ART
Computerized relational databases are used to form information systems
which model real world issues and are composed of objects, the
relationships i.e., facts, between those objects and the constraints and
rules which govern these relationships and objects. Objects are physical
or logical entities, capable of being uniquely identified. In this
respect, objects are said to be essentially noun-like. Facts define the
manner in which objects interact with one another, and are essentially
verbs or are verb-like. Constraints modify or constrain the
inter-relationships between objects and facts, and as such are analogous
to adverbs and pronouns. As the use of information systems increases and
the design of such systems advance, so increases the complexity of the
real world issues they are expected to accurately model.
In creating an information system, a user needs to accurately transform the
real world model, also known as the external view of the data, to its
actual physical implementation, using a particular database language on a
particular computer system. This implementation is also called the
physical view. In order to realize the power inherent in relational
databases, it must be made possible for someone with no computing
background or education to be able to design and implement information
management systems and query meaningful data from them without having to
learn a specific computer language.
The physical view of an information system is expressed in one of a number
of database design languages. Examples of database design languages well
known to those skilled in the art include Structured Query Language (SQL)
and Microsoft Access. These database design languages are well adapted to
carry out the storage and subsequent retrieval of data stored therein, but
the languages themselves are both unnatural and highly technology
specific. This means that database design languages are not typically used
or understood by the end users of the information systems the languages
model. The use of these design languages is a largely intuitive process
practiced by database analysts who are familiar with the internal
complexities of such languages.
The transformation of an information system from its external view to its
physical view is time consuming, and at once formalized while remaining
something of an art form. In order to assist database analysts in modeling
data for information system design, several Computer Aided Software
Engineering (CASE) tool sets have been developed, and are well known to
those skilled in the art.
Prior art CASE tool sets were generally based upon entity-relationship
modeling (ER). ER models, while providing a useful means of summarizing
the main features of an application, are typically incapable of expressing
many constraints and derivation rules that commonly occur in that
application. An overview of ER-base tools may be found in Ovum (1992) and
Reiner (1992) A state-of-the-art example is discussed in Czejdo et at.
(IEEE Computer, March 1990, pp. 26-37).
In order to capture much more of the detail of an application, object-role
modelling (ORM), also known as fact-oriented modeling, was developed. Well
known prior art versions of ORM include Natural-Language Information
Analysis Method (NIAM), Binary-Relationship Modelling (BRM), Natural
Object Role Modelling (NORM), and Predicator Set Model (PSM). One version
of ORM, Formal Object Role Modelling (FORM) is based on extensions to NIAM
and has an associated language (FORML) with both graphical and textual
forms (Halpin and Odowska, 1992). FORM and FORML were developed in part by
one of the inventors of the present invention.
The use of symbol-driven CASE tool sets provides a powerful instrument for
conceptualizing the model of a given information system, but their use is
not intuitively obvious to the untrained user. For such a user, being able
to model information systems using a language with which the user is
already facile is a more powerful approach. FORML provides the user with a
natural language-like command set, and is thus readily learned.
Several CASE tool sets for object-role modeling exist. Among those known by
persons skilled in the art are RIDL (Detroyer et at, 1988; Detroyer 1989;
Nienhuys-Cheng 1990), GIST (Shoval et al, 1988) and IAST (Control Data,
1982). RIDL is currently marketed by Intellibase. These ORM-based CASE
tool sets generally conform only to a binary-only version of ORM, although
RIDL has recently added support for fact types of higher arity. In
general, these systems are based upon the explicit "drawing" of symbols on
diagram. Users of these tool sets typically specify their information
systems by placing symbols directly on diagrams. In the typical CASE tool
set, a different tool is used for each type of symbol used. The emphasis
in these tool sets is on the notation of the symbols and what they mean,
not the underlying semantics of the language upon which the notation
rests.
An "optimal normal form" method for mapping from ORM to normalized
relational tables was introduced in NIAM in the 1970's. This method
ignored certain cases and provided a very incomplete specification of the
methodology for constraint mapping. A significant extension of NIAM,
capable of completely mapping any conceptual schema expressed in the
graphic version of FORML to a redundancy-free, relational schema, was
introduced as RMAP (Relational Mapping, Ritson and Halpin, 1992). RMAP
differs from other mapping methods, such as RIDL-M, by enabling a wider
variety of constraints; e.g., n-ary subset, equality, exclusion, closure
and ring constraints.
Database professionals, using ORM-based CASE tool sets are markedly more
productive than similar workers without them. A tool set which contains a
mapping schema such as RMAP is even more powerful, and results in further
productivity. FORML based tool sets which implement RMAP represent the
current state of the art with respect to ORM-based tool sets. Given
FORML's graphical and textual language forms, the potential exists to
combine the power, flexibility and precision of ORM based CASE tool sets
with the ease and rapidity of use of graphical user interfaces common in
modem computer systems. This will have the effect not only of further
increasing the productivity of CASE tool sets in the hands of computer
professionals, but will place these powerful software engineering tools in
the hands of heretofore naive users as well.
While prior art natural language CASE tools do fulfill some of the promise
of their basic concept, they lack the power of the symbol driven systems
to model complex databases with facility. Until the present invention,
there existed no CASE tool set for database design which combined the
power, flexibility and accuracy of ORM using natural language-like
constructs with a graphical user interface to translate the natural
language-like constructs into ORM symbology and automatically map the
conceptual schema so formed into a relational schema for implementation on
a number of SQL-like database languages. The present invention effects a
six-fold reduction in the number of user operations necessary to draw
symbols on ORM-based diagrams by allowing users to type information in an
approximately natural language. Users can think about the semantics of
information and not waste time laboring on symbol drawing, which dampens
the semantic thought process.
In addition to the ER and ORM-based prior art tool sets previously
discussed, there have been efforts by other workers to automate the
process of database specification using different methodologies. Some of
the more pertinent attempts are described below.
U.S. Pat. No. 4,688,196 to Thompson et. al. teaches a natural language
interface generating system which allows a naive user to create and query
a database based on a system of menu-driven interfaces. As the user
addresses command words, in a natural language, to the interface
generating system it provides a menu of words which could legally follow
each word as it is input. The menu is provided by referencing pre-defined,
resident files. Thompson calls these flies grammars and lexicons. The
commands input by the user are translated by the system, which then
provides an automatic interactive system to generate the required
interface in the following manner. After the database is loaded in, the
interface generating system poses a series of questions to the user's
technical expert. In response to these questions, the user or his expert
must identify which tables in the database are to be used; which
attributes of particular tables are key attributes; what the various
connections are between the various tables in the database and what
natural language connecting phrases will describe those relations.
U.S. Pat. No. 4,939,689 to Davis et. al. teaches a system for the creation
of database structures and subsequent querying of those structures by use
of a text driven outliner system. The Davis system uses another form of
resident dictionary table, which is again previously defined. In Davis,
the user inputs a textual outline which defines the format of the
database. This outline is then used to create data entry screens to
facilitate data entry.
After creating database information systems (and assuming the data to
populate those systems has been input), the information system must be
accurately queried. Efforts by others skilled in the present art teach two
broad strategies to enable the naive user to form queries.
The first prior art solution to the query generation problem is through the
use of natural language parsers. This methodology takes a query which is
input in a desired natural language such as English or Japanese, and
parses the query into its component parts. Each component of the query is
then used to form the translation of the original natural language query
into a database language query. Until the present invention, this was
typically accomplished by some form of resident database or dictionary
file which translated the parsed command words and phrases into their
respective equivalents in the database design language.
European Patent Application EP 0522591A2, filed 10 Jul., 1992 by Takanashi
et. al., teaches a system typical of this "parse and look up" strategy,
whereby a natural language query is entered and parsed into its
constituent parts. The parser uses both a resident grammar table and a
resident terminology dictionary to translate the meaning of individual
command words and phrases into the database design language. The
difficulty with fully implementing this solution is the richness and power
i.e., the size and variable structure, of most natural languages. Each
possible word and many phrases must have a corresponding entry in the
resident tables to make the system truly utile. If this is not done, the
power of the natural language interface is substantially weakened in that
a command will not be understood by the system.
The cost, both monetary and in computer overhead, of creating and
maintaining a large, full-time resident natural language interface to any
substantial information system is prohibitive. Furthermore, end users are
still required to know the types of questions and keywords the parser and
resident dictionary files will understand. This is because the resident
table methodology does not fully account for the relationships between
data objects and the constraints on those objects. For example, if a user
wants to know Mr. Smith's age, it is not sufficient to ask "How old is
Smith?" since Smith might be a person or the Smith Tower. Instead the user
must type "How old is the person called Smith?". As a result, the learning
curve for using natural language parsers is still extremely high.
The second solution to the query generation problem in the prior art is
through the use of query tools. Query tools are based on the physical
structures of the database and not the information contained therein.
Information can be broadly categorized as a set of interacting conceptual
objects, i.e. things you want to store--e.g., Person, Address, etc. Facts
are relationships between objects--e.g. a Person lives at an address. When
information is stored in a database, it is represented as a set of
physical structures, e.g. tables. Absent considerable database expertise
on the part of an end user, the physical representation of the data is
invariably unintelligible to him or her. To enable, therefore, such a
naive user to query data based on the physical structure it is stored in
will require a significant training effort to ensure understanding of
these physical structures.
In formulating a query using either a natural language parser or a physical
structure query tool, one final issue remains. The user can never be sure
that the query which is ultimately formed by either process is actually
phrased correctly. When querying physical structures, absent significant
training, the naive user doesn't understand the manner in which the data
was stored. When using a natural language parser, the same problem arises
due to the ambiguity inherent in that natural language. If, for instance,
a user asked "How old is Smith?", and the computer answers "55", the
answer may be for the person Smith, or the Smith Tower. This is
reminiscent of the experience of a reporter who telegraphed Cary Grant's
agent, asking about Mr. Grant's age. The reporter, sensitive to the cost
per word of sending a telegraph, queried "HOW OLD CARY GRANT?". The actor,
when the telegraph was inadvertently delivered to him, replied, again by
telegraph, "OLD CARY GRANT JUST FINE". Clearly, unless the syntax of the
query is correct, a naive user may retrieve an uncertain answer or an
answer to an unintended query.
A common design feature of prior art CASE tools as previously discussed is
the use of a pre-defined table or tables both to effect the translation of
natural language inputs and to specify the exact nature of the data
objects, facts and constraints as well as the interrelationships
therebetween. As discussed, this methodology is costly, inefficient and
not fully effective.
A further design feature of CASE tools currently in use for information
system specification is their use of symbols instead of a natural
language. A symbology-driven CASE tool set is at once imprecise and
cumbersome, requiring several steps to perform the transformation from a
chart of symbols to a database specification in a computer language.
There is therefore a need for apparatus that allows users to specify and
create an information system using natural language or natural
language-like commands, which will precisely specify the system's objects,
facts and constraints without ambiguity or excessive overhead. This means
should be capable of graphical depiction to define the interrelationships
among the data elements in an unambiguous manner. The information used to
create the system should be useable to define both the structure of the
database itself as well as subsequent queries to that database once it is
completed. There is a another need for a means for a naive user to be able
to specify these queries to the system, again using natural language like
commands which are not bound by previously entered definitions in a
translation table. There is yet another need for a means for ensuring that
any query which is created for the purpose of accessing the information
system will, precisely and again without ambiguity, convey the user's
intended question and return a correct, unambiguous answer.
DISCLOSURE OF INVENTION
The present invention provides a method and apparatus that allows users to:
1. Develop an information system description using a graphical user
interface to a natural language-like computer language. One such language
is FORML.
2. Specify the fact tree for query generation.
3. Check queries for semantic correctness.
4. Generate queries to the database system.
Once it has been determined that an information system needs to be created,
the Fact Compiler of the present invention is invoked. The Compile
function of the Fact Compiler enables a user to type in text, using a
natural language-like computer language. One such language is FORML. The
text is typed in a window provided by the system, and may contain objects
(also referred to herein as nouns), facts (also referred to herein as fact
types or sentences) and/or constraints. Using a translation function
called "Drag and Drop over Diagram" and a graphical user interface, the
user then drags the text from the entry window to the appropriate place
over the ORM conceptual schema diagram of the Fact Compiler. The user then
drops the text onto the diagram. The Fact Compiler validates the text
entered and notifies the user of any errors encountered. During
validation, the Fact Compiler first parses the text and creates an object
list, a fact list and a constraint list in memory. Then the Fact Compiler
iteratively compiles the text into the repository. The repository is
essentially a "database of databases". Finally, the validated objects,
facts and/or constraints are drawn in proper notation on the ORM
conceptual schema diagram. At this point the information system
specification may be considered complete.
After the information system has been created, the user may wish to check
and/or edit the previously entered information. This is accomplished by
using the Decompile function of the Fact Compiler. Decompile is
essentially the reverse of the previously discussed Compile function, in
that it takes an ORM conceptual schema diagram and returns a textual
listing of the objects, facts and constraints entered in the repository.
The user can use this listing to verify the information system
specification or to edit the system as it exists.
Once the information system specification is complete, the conceptual
schema depicted in the ORM representation of the information system is
mapped to a relational database using RMAP. The RMAP process is fully
described in McCormack et al (1993), which is incorporated by reference as
if fully set forth herein. By way of example, for an example set of facts:
Person lives at address
Person has Phone Number
Person studies Subject
Subject is taught by Person
if the relational database associated with an example fact tree is:
______________________________________
Person.sub.- Table:
(Person, Address)
Phone.sub.- Table:
(Person, Phone Number)
Studies.sub.- Table:
(Person, Subject Studied)
Subject.sub.- Table:
(Subject, Teacher Person)
______________________________________
The associated RMAP mappings would be:
__________________________________________________________________________
FACT TABLE FIRST NOUN COLUMN
SECOND NOUN COLUMN
__________________________________________________________________________
Person lives at address
Person.sub.- Table
Person Address
Person has Phone Number
Phone.sub.- table
Person Phone Number
Person studies Subject
Studies.sub.- Table
Person Subject Studies
Subject is taught by Person
Subject.sub.- Table
Person Teacher Person
__________________________________________________________________________
The first step in query processing is specifying the fact-tree. In
Fact-Tree Specification, the user selects a noun relevant to the query.
For example, if the user wanted to find out the address, phone number,
subjects studied, and teachers of Mr. Smith, they would start with the
Person noun because the query is basically about a person. After choosing
Person as the root of the query, they can select more information about
the person--to find out their address etc. The only information they are
able to select is the information contained in the facts about the person,
i.e.
O A person lives at an address.
O A person has a phone number.
O A person studies a subject.
O A person teaches a subject.
This set of facts is all of the information possible about a particular
person. The information is displayed conceptually and the user didn't need
to know any special keywords or phrases. In this case the user would
select the facts
O A person lives at an address.
O A person has a phone number.
O A person studies a subject.
O A subject is taught by a person.
since that is what they want to know about Mr. Smith. This would build up
the following fact-tree.
______________________________________
Person
.sub.- that lives at an address
.sub.- that has a phone number
.sub.- that studies a subject
.sub.- that is taught by a person.
______________________________________
Finally, the user would restrict the person at the root of the tree to be
equal to Mr. Smith, since this is the only person they are interested in.
The meaning of the final tree is: Show the person Mr. Smith, the address
that he lives at, the phone numbers that he has, the subject that he
studies, and for the subjects he studies, show the people that teach those
subject.
After generating the fact-tree, the user verifies that the fact-tree is
correct using the Tree Interpreter of the present invention. Doing so will
preclude the possibility of an ambiguous query being generated. In use,
the Tree Interpreter algorithm constructs a natural language description
of the fact-tree. This algorithm is a recursive depth-first search
function which is described in the following best mode section. This
interpretation allows the user to verify that the question he or she is
asking will retrieve the information desired.
Once the user has specified the fact-tree and checked it using the Tree
Interpreter, all that remains to do is generate the relational query
itself. The algorithm to do this is again recursive on fact-tree nodes,
and is detailed in the following section detailing the best mode of
carrying out the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The various features and advantages of the present invention may be more
readily understood with reference to the following detailed description of
the preferred embodiments taken in conjunction with the accompanying
drawings, wherein like reference characters designate like elements.
FIG. 1 is a diagram of the external view of a digital, programmable,
general purpose computer configured for operation of the present
invention.
FIG. 2 is a block diagram of the computer of FIG. 1 configured with the
present invention.
FIG. 3 is a flow chart illustrating the initial selection menu of the
present invention, after selecting the Fact Compiler of the present
invention.
FIG. 4 is a flow chart illustrating the Fact Compiler of the present
invention, including it's three main functions.
FIG. 5 is a flow chart illustrating the Drag and Drop over Diagram function
of the Fact Compiler of the present invention.
FIG. 6 is a flow chart of the Drag and Drop Parse function invoked by the
Drag and Drop over Diagram function.
FIG. 7 is a flow chart of the Compile into Repository Only function invoked
by the Fact Compiler.
FIG. 8 is a flow chart of the Parse function invoked by the Compile into
Repository Only function.
FIG. 9 is a flow chart of the Scan function invoked by the Parse function.
FIG. 10 is a table indicating the procedure for entering an error condition
according to the present invention.
FIG. 11 is a flow chart illustrating the Look for Object Specifications
function invoked by the Parse function.
FIG. 12 is a flow chart representing the Look for Fact Specifications
function invoked by the Parse function.
FIG. 13 is a flow chart representing the Look for Constraint Specifications
function invoked by the Parse function.
FIG. 14 is a flow chart illustrating the Allocate a New Object function
invoked by the Look for Object Specifications function.
FIG. 15 is a flow chart illustrating the Allocate a New Fact function
invoked by the Look for Fact Specifications function.
FIG. 16 is a flow chart illustrating the Allocate a New Constraint function
invoked by the Look for Constraint Specifications function.
FIG. 17 is a flow chart representing the Update Record in Repository
function invoked by both the Drag and Drop Parse and Compile into
Repository Only functions.
FIG. 18 is a flow chart illustrating the initial selection menu of the
present invention, after selecting Fact Tree Specification according to
the present invention.
FIG. 19 is a flow chart illustrating the Fact Tree Formation function and
selection of either the Query Mapper or Tree Interpreter functions of the
present invention.
FIG. 20 is a flow chart representing the Fact Tree to SQL Query function
invoked when a user selects the Query Mapper function of the present
invention.
FIG. 21 is a flow chart illustrating the Node to SQL function invoked by
the Fact Tree to SQL function.
FIG. 22 is a flow chart representing the Create Join function invoked by
the Node to SQL function.
FIG. 23 is a flow chart illustrating the Add Selector 1 function invoked by
the Node to SQL function.
FIG. 24 is a flow chart illustrating the Add Selector 2 function invoked by
the Node to SQL function.
FIG. 25 is a flow chart of the Fact Tree to Description function invoked
when a user selects the Tree Interpreter of the present invention.
FIG. 26 is a flow chart of the Create Text for Root function invoked by the
Fact Tree to Description function.
FIG. 27 is a flow chart illustrating the Create Text for Node function
invoked by the Fact Tree to Description function.
BEST MODE OF CARRYING OUT THE INVENTION
The preferred embodiment of the present invention incorporates computer
system 1 configured as shown in FIG. 1. Computer system 1 is a
programmable digital computer. The invention is executable on an IBM
compatible computer having an Intel 80386 or higher chip set, operating
under the MS-DOS operating system, version 5.0 or higher. A minimum or 6
megabytes of available RAM is required for execution, as is a minimum of 6
megabytes of available hard disk storage space. These computers typically
include a CPU, main storage, I/O resources, and a user interface,
including a manually operated keyboard and mouse. The present invention
also requires a graphical user interface program: Microsoft Windows is one
well known example.
The present invention was programmed on an IBM compatible computer having
an Intel 80486 chip set, running Microsoft MS-DOS operating system,
version 5.0. Microsoft Windows Version 3.1 was installed to provide the
required graphical user interface. Finally, the system whose description
follows was programmed in the Borland C language.
FIG. 2 depicts the bus structure of the general purpose programmable
computer of FIG. 1, with the present invention implemented thereon.
Referring now to FIG. 3, a user initiates the system at manual input 50 and
selects the desired function at function selection 51.
The present invention provides a method and apparatus that allows users to:
1. Develop an information system description using a graphical user
interface to a natural language-like computer language. One such language
is FORML.
2. Specify the fact tree for query generation.
3. Check queries for semantic correctness.
4. Generate queries to the database system.
Once it has been determined that an information system needs to be created,
the Fact Compiler of the present invention is invoked. The Compile
function of the Fact Compiler enables a user to type in text, using a
natural language-like computer language. One such language is FORML. The
text is typed in a window provided by the system, and may contain objects,
facts and/or constraints. Using a translation function called "Drag and
Drop over Diagram" and a graphical user interface, the user then drags the
text from the entry window to the appropriate place over the ORM
conceptual schema diagram of the Fact Compiler. The user then drops the
text onto the diagram. The Fact Compiler validates the text entered and
notifies the user of any errors encountered. During validation, the Fact
Compiler first parses the text and creates an object list, a fact list and
a constraint list in memory. Then the Fact Compiler iteratively compiles
the text into the repository. The repository is essentially a "database of
databases". Finally, the validated objects, facts and/or constraints are
drawn in proper notation on the ORM conceptual schema diagram. At this
point the information system specification may be considered complete.
After the information system has been created, the user may wish to check
and/or edit the previously entered information. This is accomplished by
using the Decompile function of the Fact Compiler. Decompile is
essentially the reverse of the previously discussed Compile function, in
that it takes an ORM conceptual schema diagram and returns a textual
listing of the objects, facts and constraints entered in the repository.
The user can use this listing to verify the information system
specification or to edit the system as it exists.
Once the information system Specification is complete, the conceptual
schema depicted in the ORM representation of the information system is
mapped to a relational database using RMAP. The RMAP process is fully
described in McCormack et al (1993), which is incorporated by reference as
if fully set forth herein. By way of example, for an example set of facts:
Person lives at address
Person has Phone Number
Person studies Subject
Subject is taught by Person
if the relational database associated with an example fact tree is:
______________________________________
Person.sub.- Table:
(Person, Address)
Phone.sub.- Table:
(Person, Phone Number)
Studies.sub.- Table:
(Person, Subject Studied)
Subject.sub.- Table:
(Subject, Teacher Person)
______________________________________
The associated RMAP mappings would be:
__________________________________________________________________________
FACT TABLE FIRST NOUN COLUMN
SECOND NOUN COLUMN
__________________________________________________________________________
Person lives at address
Person.sub.- Table
Person Address
Person has Phone Number
Phone.sub.- table
Person Phone Number
Person studies Subject
Studies.sub.- Table
Person Subject Studies
Subject is taught by Person
Subject.sub.- Table
Person Teacher Person, if the relational
database associated with an
example fact tree is:
__________________________________________________________________________
The first step in query processing is specifying the fact-tree. In
Fact-Tree Specification, the user selects a noun relevant to the query.
For example, if the user wanted to find out the address, phone number,
subjects studied, and teachers of Mr. Smith, they would start with the
Person noun because the query is basically about a person. After choosing
Person as the root of the query, they can select more information about
the person--to find out their address etc. The only information they are
able to select is the information contained in the facts about the person,
i.e.
O A person lives at an address.
O A person has a phone number.
O A person studies a subject.
O A person teaches a subject.
This set of facts is all of the information possible about a particular
person. The information is displayed conceptually and the user didn't need
to know any special keywords or phrases. In this case the user would
select the facts
O A person lives at an address.
O A person has a phone number.
O A person studies a subject.
O A subject is taught by a person.
since that is what they want to know about Mr. Smith. This would build up
the following fact-tree.
______________________________________
Person
.sub.- that lives at an address
.sub.- that has a phone number
.sub.- that studies a subject
.sub.- that is taught by a person.
______________________________________
Finally, the user would restrict the person at the root of the tree to be
equal to Mr. Smith, since this is the only person they are interested in.
The meaning of the final tree is: Show the person Mr. Smith, the address
that he lives at, the phone numbers that he has, the subject that he
studies, and for the subjects he studies, show the people that teach those
subject.
After generating the fact-tree, the user verifies that the fact-tree is
correct using the Tree Interpreter of the present invention. Doing so will
preclude the possibility of an ambiguous query being generated. In use,
the Tree Interpreter algorithm constructs a natural language description
of the fact-tree. This algorithm is a recursive depth-first search
function which can be summarized as follows:
__________________________________________________________________________
function: Interpret.sub.- Tree (fact-tree.sub.- node) Il Interpret.sub.-
Tree operates on a node of
the fact-tree
begin
If the node is the root of the tree then
noun is the noun in the node
e.g. Person
Print `For all noun(s)` e.g. For all Person(s)
if the node has a restriction then
e.g. is equal to Mr. Smith
print "(where noun restriction)"
e.g. (where Person = Mr.Smith)
Print "show:" and move on to a new line
otherwise
noun is the noun in the node e.g. Address
parent-noun is the noun in the node's parent
e.g. Person
phrase is the phrase in the noun
e.g. lives at
Print "the noun(s) that the parent-noun phrase"
e.g. the Address(es)
that the person
lives at
if the node has a restriction then
e.g. is equal to
Seattle
print "(where noun restriction)"
e.g. (where address
= Seattle)
if the node has any children then
print ", and for those noun(s) show:"
move on to a new line
for all children of the node do
call Interpret.sub.- Tree on the child-node
end
__________________________________________________________________________
The result of Interpret.sub.-- Tree on the example fact-tree would be
For all Person(s) (where Person=Mr. Smith) show:
the Address that the Person lives at
he Phone Number that the Person has
the Subjects that the Person studies,
and for those subjects show the Person(s) that the Subject is taught by.
This interpretation allows the user to verify that the question he or she
is asking will retrieve the information desired.
Once the user has specified the fact-tree and checked it using the tree
interpreter, all that remains to do is generate the relational query
itself. The algorithm to do this is again recursive on fact-tree nodes.
function Create.sub.-- Query (fact-tree.sub.-- node)
begin
node is the node being mapped by this call to the function
childi . . . childn are the children of node
sentence1, . . . sentencen. are the respective sentences for childi . . .
childn each sentence i, (i=1 . . . n) has a mapping' associated with it.
The mapping corresponds to the relational structure used to represent the
sentence and contains the table that the sentence was mapped to, the
column for the first noun and the column for the second noun. For example,
the sentence Person lives at Address maps to the Person table, with noun1
(person) being column 1, and noun2 (address) being column 2.
Join all of the mappings for sentences 1..n together using outer joins
based on the noun in node and the respective positions of that noun in
sentences 1 to n. Form a query, including restriction when required.
An SQL query representative of this applied to the example fact-tree would
be:
select: Person. Person, Phone Number, Subject
from Person, Person has Phone.sub.-- Number, Person.sub.-- studies.sub.--
Subject
Outer join Person.Person=Person has Phone.sub.-- Number.Person
Outer join Person.Person=Person.sub.-- studies.sub.-- Subject.Person
where Person.Person=`Mr. Smith` . . .
If any childi i=1..n have children, apply Create.sub.-- Query to child and
use an outer join to include the result into the existing query. In the
example fact-tree, this would result in Create.sub.-- Query being executed
on the Subject node of the Person that studies Subject branch and would
result in the query:
select Person.Person, Phone Number, Person.sub.-- studies.sub.-- Subject.
Subject Subject.Person
from Person, Person.sub.-- has.sub.-- Phone Number, Person.sub.--
studies.sub.-- Subject, Subject
Outer join Person.Person=Person.sub.-- has.sub.-- Phone.sub.--
Number.Person
Outer join Person.Person=Person.sub.-- studies.sub.-- Subject.Person
Outer join Person.sub.-- studies.sub.-- Subject.Subject=Subject.Subject
where Person.Person=`Mr. Smith . . .
Note that SQL is used as a notational convenience and its use has no
bearing on the theory behind the algorithm. It is a particular feature of
the present invention that any relational language could have been used.
The advantages of the Fact Compiler, Query Mapper and Tree Interpreter
algorithms of the present invention are that they substantially reduce the
number of concepts and amount of training required for a naive end-user to
express meaningful queries in a relational database. The algorithm set of
the present invention allows users to form conceptual queries without
having to know keywords and physical structures. Also, the algorithms of
the present invention provide a generated natural language description of
the query to assure that the query is correct in syntax. These advantages
are illustrated by contrasting the previously described example with the
same example expressed in the state of the art natural language and SQL
implementations.
To express the query in natural language, the user would need to construct
and type in the query:
Show me the person called Mr. Smith, his Address, his Phone Number, the
subjects he studies, and for those subjects show people who teach them
The distinct pieces of information required to phrase this query are:
1. An overall knowledge of how to express the query (having to include
keywords like person, etc.)
2. The knowledge that you could ask for Address, Phone Numbers, Subjects,
etc . . .
Fact Compiler
The fact compiler of the present invention is selected at 100. The fact
tree of the present invention is selected at 300. As explained above, a
Fact Compiler is provided by the present invention, a detailed description
of which follows. Referring now to FIG. 4, after selecting fact compiler
100, the user opens a diagram which represents one level of the
information system to be modelled. After opening the fact compiler
diagram, the user types in a factual sentence, an object type, or a
constraint, using a natural language-like computer language. One such
language is FORML. An example of such an input is "the INSTRUCTOR with the
ID "100" is qualified to teach the SUBJECT with the name "database design"
at the SUBJECT LEVEL 300". At this point, the user may select one of three
options: validate the input using Validate Only function 105; compile the
information only into the repository 140; or to drag and drop the fact
over the diagram at function 120.
Referring now to Validate. Only function 105 of FIG. 4 of the present
invention, after all text has been combined from the edit windows at 110,
it is parsed into its component words using function 111. An error checker
at 112 determines if there are errors in the text which is input. If there
are no errors, the system indicates successful validation at 113. If error
checker 112 determines that there are errors in the textual input, the
errors will be shown at error window 114.
Drag and Drop over Diagram function 120, is detailed in FIG. 5. After the
user selects Drag and Drop over Diagram at 120, the user utilizing a mouse
moves a pointer over the icon from the edit window at 121. The user
presses the left mouse button down and holds it down at 122. The system
will test for the type of item which was input in the edit window at 123.
Item kind selector 124 will change the nature of the cursor depending upon
the type of information input in the edit window. If the data input is a
fact, the cursor will change to a fact cursor at 125. If the data input is
a constraint, the cursor will be changed to a constraint cursor at 126. If
the data input is an object, the cursor will change to an object cursor at
127. The user drags the modified cursor over the diagram at 128. The edit
window will disappear while the cursor is being moved. If the cursor moves
over a non-drawing area the cursor change to a "Can't Draw" cursor. In the
event the user needs to reorient the direction of the data which is input,
the right mouse button is used. For each click of the right mouse button,
the icon changes its orientation 90.degree. at 130. When the user releases
the left mouse button at 131, the cursor will drop the data over the
diagram. Cursor checker 132 determines if the cursor is actually over the
diagram or not. If it is, Drag and Drop Parse function 135 is invoked. If
not, an indication is given the user that the cursor is not in the
diagram.
Drag and Drop Parse function 135 is detailed in FIG. 6. After collecting
text at the current edit window, the text is parsed using Parse function
142. After parsing an error checker 161 determines if an error has been
made in the textual input. If no error has been made, the record is
updated to the repository using the Update Record to Repository function
149. After the record has been updated to the repository, the item is
drawn on the diagram using Draw Item on Diagram function 164. At error
checker 161, should an error condition be determined to exist, Enter Error
Condition function 162 is invoked and function 135 exited at 165.
Referring again to FIG. 4, function 140 gives the user the option of
compiling the input into the repository only. Function 140 is detailed in
FIG. 7. After selecting function 140, Compiling into Repository Only, the
system combines all text from the edit windows at 141 and parses the input
data using Parse function 142. Error checker 143 determines if an error
has been made in the textual input. If errors have been made, they are
shown at error window 145. In the event no errors were incurred,
successful compilation is shown in the status bar at 144. An iterative
process is detailed at 146. Each of the lists generated, the object list,
fact list and constraint list, is searched record by record. Each record
is retrieved from it's respective list at 147 and its status tested at
148. In the event the record has been changed, function 149, which updates
the record to the repository, is invoked. In the event the record has not
been changed, the list pointer is incremented at 150 and a new record is
retrieved from the list. In the event the record is new, function 149 is
again invoked after which the record type is tested at 152. If the new
record is an object, function 152, which allocates a new object, is
invoked. In the event the new record is a fact, a new fact is allocated
using function 154. If the new record type is a constraint, a new
constraint is allocated at 155. Following any of these allocations, the
list pointer is again incremented at 150.
Parse function 142 of FIGS. 6 and 7 is detailed at FIG. 8. After Parse
function 142 is invoked, it invokes Scan function 170 to retrieve a token.
After the token is retrieved, it is partitioned into sections at 171. An
iterative loop through each of the tokens is set up at 172. Each token is
tested for its type at 173. In the event the section is an object,
function 174, which looks for object specifications, is invoked. In the
event the section is a fact, function 175, which looks for fact
specifications is invoked. In the event the section being tested is a
constraint, function 176 is invoked which looks for constraint
specifications. After either functions 174, 175 or 176 have been invoked,
a test is made to determine if the section tested is the terminal section.
If not, the next section is subjected to the same test. In the event the
section is a terminal section, Parse function 142 is exited at 179.
Scan function 170 of FIG. 8 is detailed at FIG. 9. After Parse function 142
invokes Scan function 170, it reads characters from the input source text
at 180. At 181, the function matches each. character sequence with a token
specification shown as regular expressions in the Lexical Analyzer
Declarations at 181, after which the token is returned at 182.
Function 162, Enter Error Condition which was previously invoked at FIG. 6,
is detailed at FIG. 10. For each error encountered, the system will
retrieve the character position and line number where the error occurred.
This function will then store the error number, error text and error
context information in an error list.
Referring again to FIG. 8, function 174, Look for object Specification, is
detailed at FIG. 11. When function 174 is invoked, the object is
syntactically specified by any "Object Declaration" at 190. The function
continues to "parse" and "scan". A determination is made at 191 as to
whether it is still an object section. If not, the function exits at 192.
If the object is still in the object section, it breaks the textual
components into structures for storing in the object list at 193. At 194,
the object status is tested. If it is a new object, function 220 which
allocates a new object, is invoked, If the object already exists in an
object list, function 174 is exited at 198. If the object exists in the
repository but it is not in the object list, the system reads the
structure at 196 from the repository and puts it in the object list. After
either function 196 or 220 is invoked, the function is again exited at
198.
Function 175, Look for Fact Specification, previously invoked at FIG. 8, is
derailed in FIG. 12. After function 175 is invoked, the fact is
syntactically specified by a "fact declaration". The system continues to
"parse" and "scan". A determination is made at 201 as to whether the fact
is still in the fact section. If not, function 175 is exited at 202. If it
is still in the fact section, the system breaks the textual components
into structures for storing in a fact list at 203 after which the fact
status is tested at 204. If the fact is a new fact, function 230 is
invoked, which allocates a new fact after which fact parsing is exited at
206. If the fact already exists in a fact list, the function 175 again
exits at 206. If the fact exists in the repository but is not in the fact
list, the system reads the structure at 205 from the repository and puts
it in the fact list, after which function 175 exits once again at 206.
Function 176, also previously invoked at FIG. 8, is derailed at FIG. 13.
When function 176 is invoked to look for constraint specifications, a
constraint is syntactically specified by a "constraint declaration" at
210. The system continues to "parse" and "scan". At 211 a determination is
made if the constraint is still in the constraint section. If not,
function 176 is exited at 212. If the constraint is still in the
constraint section, the system breaks the textural components into
structures for storing in the constraint list at 213. After which the
constraint status is tested at 214. If a new constraint, function 240 is
invoked, which allocates a new constraint. If the constraint already
exists in the constraint list, function 176 is exited at 217. If the
constraint exists in the repository but it is not in the constraint list,
the function reads the structure from the repository and puts it in the
constraint list at 216. After either function 240 or process 216 is
accomplished, function 176 exits at 217.
Function 220, previously invoked in FIG. 11, is detailed in FIG. 14.
Function 220 creates an empty object structure at 221, enters the name and
all object attributes into the structure at 222, places the object
structure in the object list at 223, and exits at 224.
Function 230, previously invoked in FIG. 12, is detailed in FIG. 15.
Function 230 creates an empty fact structure at 231. At 232 the function
puts the predicate text, the objects involved and internal constraint
information into the structure. At 233, the function places the fact
structure into the fact list and exits at 234.
Function 240, previously invoked at FIG. 13, is detailed in FIG. 16.
Function 240 allocates a new constraint as follows: it creates an empty
constraint structure at 241. At 242 it puts the constraint information
(role positions, predicate IDs) into the structure. At 243 the function
places the constraint structure into the constraint list and exits at 244.
Function 149, previously invoked in both FIGS. 7 and 8, is detailed in FIG.
17. After function 149 is invoked, an updated record exists in a fact
list, an object list or a constraint list, as shown at 250. At 251, the
record type is tested. If the record is an object, the object structure is
sent the object update function at 252. If the record is a fact, the fact
structure is sent to the fact update function at 254 and if a constraint
structure is sent to a constraint update function at 253. After any of the
aforementioned update functions is accomplished, function 149 is exited at
256.
Fact Tree Formation
Referring to FIG. 18, the second option possible from function selection 51
is initiation of Fact Tree Specification 300, which is detailed at FIG.
19.
Referring to FIG. 19, the fact-tree is formed at 300. An example of a fact
tree is:
______________________________________
Person (= Mr Smith) . . . . . . . . . . . . . . .restriction
.linevert split.-- that person lives at an address
.linevert split.-- that has a phone number . . . . . . . . . . . . . .
.noun
.linevert split.-- that studies a subject
.linevert split.-- that is taught by a Person
.linevert split. . . . . . . phrase"
______________________________________
Each node in the fact tree has a noun (e.g. Person).
Each node in the fact tree may have a restriction (e.g.=Mr Smith).
Each non-root node in the fact tree (all but the very top node) has a
phrase (e.g. is taught by).
The root of the tree is then assigned to the variable Root at 301. In this
case, the shaded node (Person) is assigned to Root.
If the fact tree is to be mapped to an SQL query, Root is passed as the
parameter to the function Fact.sub.-- Tree.sub.-- To.sub.-- SQL 400. The
return value of this function will be an SQL query. Fact.sub.--
Tree.sub.-- To.sub.-- SQL is described using functions 400 to 465.
If the fact tree is to be mapped to an English description, Root is passed
as the parameter to the function Fact.sub.-- Tree.sub.-- To.sub.--
Description (500). This function has no return value. The result of Fact
Tree To Description will be to print out the description of the tree.
Fact.sub.-- Tree.sub.-- To.sub.-- Description is described using functions
500 to 535.
Tree Interpreter
The present invention also provides a Tree Interpreter, invoked as
"Fact.sub.-- Tree.sub.-- to.sub.-- Description", a detailed description of
which follows. Referring to FIG. 25, Fact.sub.-- Tree.sub.-- To.sub.--
Description (500) is a recursive function that takes a node of a fact tree
as input and returns a description of the query represented by that tree
or sub-tree. The parameter Root is the node on which the function is to
operate.
Function 501 assigns some working variables. Root is the root of a tree of
subtree that may or may not contain a parent and may or may not contain
children. For example, if the shaded node in the example tree (Parent) was
passed to Fact.sub.-- Tree.sub.-- To.sub.-- Description, there would be no
parent, and three children. Parent is assigned Root's parent (in this case
NULL). Nodes is assigned the number of Root's children (three). Child i ..
Nodes] is an array which is assigned Root's children (the three children
of Person--"that lives at Address", "that has a phone number", and "that
studies a subject".
Next, the temporary variable Text is assigned the "description" of the
Root. (502-504). If Root has no parent (it is the root of the fact tree),
the Root is passed to the function 503 Create.sub.-- Text.sub.--
For.sub.-- Root (503), otherwise Root is passed to Function 507,
Create.sub.-- Text.sub.-- For.sub.-- Node. The return value of both of
these functions is the description of Root.
At 505, Text is then printed out followed by a carriage return. If Root
referred to the Person node, Function 503, Create Text For Root would have
been used and Text would be "For all Person(s) (where Person=Mr Smith)
show:" If Root referred to the "that studies Subject" node, function 504,
Create Text For Node would have been used and Text would be "the
Subject(s) that the Person studies, and for those Subject(s) show:".
The next step is to recursively process Root's children using a
depth-first-search algorithm, detailed in functions 505-510. Nodes is the
number of Root's children and Child i.. Nodes] are Root's actual children.
The variable I is used as a counter variable. It is initially assigned to 1
at 506. If I is greater than Nodes (there are no more children to
process), this instantiation of Fact.sub.-- Tree.sub.-- To.sub.--
Description is complete (507-508) otherwise, Fact.sub.-- Tree.sub.--
To.sub.-- Description is invoked for Childi at 509, I is incremented at
510 and the loop continues (507) until there are no more children to
process.
The result of Fact.sub.-- Tree.sub.-- To.sub.-- Description applied to the
Person node in the example tree would be:
__________________________________________________________________________
the Address that the Person lives at
Output
the Phone Number that the Person has
For all Person(s) (where Mr. Smith) show:
the Subjects that the Person studies,
and for those subjects show:
Processing
The Person(s) that the Subject
Fact.sub.- Tree To .Description called on Person
is taught by
Fact.sub.- Tree To .Description called on
that lives at Address
Fact Tree To .Description called on
that has phone number
Fact.sub.- Tree To .Description called on
that studies subject
Fact Tree To Description called on
that Is taught by Person
__________________________________________________________________________
Function 503, is invoked in FIG. 25 and Create.sub.-- Text.sub.--
For.sub.-- Root, takes the root node of a fact tree as an argument (Root)
and returns the description of that node.
At 520, Root contains a noun (e.g. Person); this is assigned to Noun. Root
may also contain a Restriction (e.g.=Mr Smith); this is assigned to
Restriction. The variable Text is assigned `For all`+noun+`(s)` (e.g. `For
all Person(s)`).
If Root contains a Restriction, that restriction is added to Text at 521
and 522. (e.g. Text="For all Person(s)(where Person=Mr Smith)")
"show": `is added to Text at 523 and
Text is returned at 524 (e.g. Text="For all Person(s)(where Person=Mr
Smith) show:").
Referring back to FIG. 25, Create.sub.-- Text.sub.-- For.sub.-- Node (504),
which takes a non-root node of a fact tree as an argument (Root) and
returns the description of that node is detailed at FIG. 27. For example,
the node `that studies a Subject` could be passed as an argument.
At 530 Root contains a noun (e.g. Subject), this is assigned to Noun. Root
contains a phrase (e.g. `studies`) this is assigned to Phrase. Root's
parent contains a noun (e.g. Person), this is assigned to Parent-Noun.
Root may also contain a Restriction (e.g.=Mr Smith) this is assigned to
Restriction. The variable Text is assigned `the`+noun+`(s) that
the`+Parent-Noun+``+Phrase (e.g. `the Subject(s) that the Person
studies`).
If Root contains a Restriction, that restriction is added to Text at 531
and 532.
If Root has children`, and for those`+Noun+`:(s) show:` is added to Text at
533 and 534.
At 535, Text is returned (e.g. Text=`the Subject(s) that the Person
studies, and for those Subject(s) show:`).
Query Mapper
The present invention also provides a Query Mapper, invoked as "Fact.sub.--
Tree.sub.-- to.sub.-- SQL.sub.-- Query", a detailed description of which
follows. Referring back to FIG. 19, function 400 is detailed at FIG. 20.
This function takes the root node of a fact tree as input and returns an
equivalent SQL query. The parameter Root is the root of the tree on which
the function is to operate.
Each non-root node in the fact tree (all but the very top node) has a
relational mapping associated with it. The relational mapping specifies
the node's representation in a relational database. By way of example, for
an example set of facts:
Person lives at address
Person has Phone Number
Person studies Subject
Subject is taught by Person
if the relational database associated with an example fact tree is:
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Person.sub.- Table:
(Person, Address)
Phone.sub.- Table:
(Person, Phone Number)
Studies.sub.- Table:
(Person, Subject Studied)
Subject.sub.- Table:
(Subject, Teacher Person)
______________________________________
The associated RMAP mappings would be:
__________________________________________________________________________
FACT TABLE FIRST NOUN COLUMN
SECOND NOUN COLUMN
__________________________________________________________________________
Person lives at address
Person.sub.- Table
Person Address
Person has Phone Number
Phone.sub.- table
Person Phone Number
Person studies Subject
Studies.sub.- Table
Person Subject Studies
Subject is taught by Person
Subject.sub.- Table
Person Teacher Person
__________________________________________________________________________
Table denotes the table in which the fact is stored. First Noun Column
denotes the column for the node's parent. Second Noun Column denotes the
column for the node's noun.
For example, the mapping associated with (Person) lives at Address means
that all addresses are stored in the Person Table table, with the people
who live at them in the Person column and the actual addresses in the
Address column.
The predicate mappings are derived by an algorithm similar to the one
described in McCormack & Halpin, Automated Mapping of Conceptual Schemas
to Relational Schemas, Proc CAiSE 93, Sorbonne University, Paris, 1993.
An SQL query contains three parts, a SelectList, a From List, and a
WhereClause. These are gradually build up using recursive calls to
Node.sub.-- To.sub.-- SQL.
Initially, SelectList, FromList, and WhereClause are set to the empty
string (" ") at 401.
At 402, Node.sub.-- To.sub.-- SQL is called, with Root as its parameter, to
build up the query.
At 403, 404 and 405, SelectList, FromList, and WhereClause are respectively
formatted. At 406, the query is assembled as the result of the function
and returned at 407.
Node.sub.-- To.sub.-- SQL is invoked at 402. This is a recursive function
that maps a node of a fact tree into an SQL query. Successive calls to
this function build up the SelectList, FromList, and WhereClause
variables.
Node.sub.-- To.sub.-- SQL has three parameters. The first, Root, is the
root of the tree or sub tree being mapped. The second and third parameters
are the table and column used to join the query for Root's sub tree to the
rest of the query.
At 410, Parent is the parent of Root, Nodes is the number of children of
Root and child [i.. Nodes] are the children of Root.
If Root has no children, no processing is required so the function simply
returns (411, 412).
Otherwise, the children of Root are added to the query as follows:
If Root has a parent, it needs to be joined into the query using the
JoinTable and JoinColumn function 413 and 414; and Root needs to be added
to the select list of the query at 415.
To join all of Root's children into the query, they are processed
sequentially as follows: The counter variable i is initialized to 1 at
416. The value of nodes is checked at 417; and if i is less than nodes
Add.sub.-- Selector.sub.-- 2 (node) is invoked at 419. Each child is added
to the select-list using Add.sub.-- Selector.sub.-- 2 at 419, and that
child's children are added into the query using recursive calls to
function 421, Node.sub.-- To.sub.-- SQL. The selector for each node is
used to join the subtree's queries together at 420. Create.sub.-- Join,
invoked at 414 is detailed at FIG. 22. This function joins a subquery to
the main query by adding an inner join to the where-clause. The join is
based in the first noun in the passes node (Node) and the passed
parameters.
Referring back to FIG. 21, function 415, Add.sub.-- Selector.sub.-- 1 is
detailed at FIG. 23. This function adds Node's table to the FromList and
the column for Node's first noun to the SelectList.
Referring again to FIG. 21, function 419, Add.sub.-- Selector.sub.-- 2 is
detailed at FIG. 24. This function adds Node's table to the FromList and
the column for Node's second noun to the SelectList.
It is to be understood that the above-described embodiments are merely
illustrative of some of the many specific embodiments which represent
applications of the principles of the present invention. Clearly, numerous
variations can be readily devised by those skilled in the art without
departing from the scope of the present invention.
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